Polyimide precursor composition and method of preparing polyimide molded article

ABSTRACT

A polyimide precursor composition includes a solvent including water and a polyimide precursor including a group having a triple bond at a terminal thereof, which is dissolved in the solvent.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority under 35 USC 119 fromJapanese Patent Application No. 2017-013522 filed Jan. 27, 2017.

BACKGROUND 1. Technical Field

The present invention relates to a polyimide precursor composition and amethod of preparing a polyimide molded article.

2. Related Art

A polyimide resin is a material having high durability and excellentheat resistance, and is widely used as an electronic material.

SUMMARY

According to an aspect of the invention, there is provided a polyimideprecursor composition including a solvent including water and apolyimide precursor including a group having a triple bond at a terminalthereof, which is dissolved in the solvent.

DETAILED DESCRIPTION

Hereinafter, exemplary embodiments of the invention will be described indetail.

Polyimide Precursor Composition

A polyimide precursor composition according to an exemplary embodimentis a composition in which a polyimide precursor in which a group havinga triple bond is provided at a terminal thereof (also referred to as “aspecific polyimide precursor” below for convenience) is dissolved in asolvent including water (referred to as “an aqueous solvent” below).That is, the specific polyimide precursor is included in a composition,in a state of being dissolved in the aqueous solvent. “Dissolution”means a state where a residue of dissolved material is not visuallyrecognized.

Here, in the related art, in a polyimide precursor composition in whicha polyimide precursor in which at least one of a carboxy group and anamide group is provided at a terminal thereof is dissolved in an aqueoussolvent, viscosity may be increased with the lapse of time and storagestability may be deteriorated.

On the contrary, if a polyimide precursor in which a group having atriple bond is provided at a terminal thereof is used as a polyimideprecursor, solubility of the polyimide precursor in an aqueous solventis increased and an increase of viscosity with the lapse of time isprevented.

Therefore, the polyimide precursor composition according to theexemplary embodiment has excellent storage stability. That is, regardingthe polyimide precursor composition according to the exemplaryembodiment, the increase of the viscosity is prevented and the polyimideprecursor composition easily retains high film preparation propertieseven after the polyimide precursor composition is stored.

Thus, by molding a polyimide molded article with the polyimide precursorcomposition according to the exemplary embodiment, a polyimide moldedarticle having excellent tensile breaking strength may be obtained.

The polyimide molded article obtained by molding with the polyimideprecursor composition according to the exemplary embodiment also hasimproved various characteristics such as mechanical characteristic(tensile elongation at break and the like other than tensile breakingstrength), heat resistance, an electrical characteristic, and solventresistance. Further, since coating performance (coating stability) ofthe polyimide precursor composition is easily kept high, an occurrenceof surface unevenness and pattern is prevented. Thus, surface smoothnessis improved and variation in quality of a polyimide molded article isalso prevented.

In the polyimide precursor composition according to the exemplaryembodiment, dispersion of various fillers which are added for impartingvarious functions to the polyimide molded article is enhanced. Thus, thehigh functions are easily exhibited even with a small amount of thefillers. The reason is considered as follows. The group which includes atriple bond and is provided at the terminal of the specific polyimideprecursor influences the filler to thereby improve dispersibility of thefiller.

Here, when a polyimide precursor composition has any configuration ofthe followings 1) to 3) in order to form a polyimide precursorcomposition having high mechanical characteristics such as tensilebreaking strength and tensile elongation at break, the viscosity of thepolyimide precursor composition is likely to be increased with the lapseof time.

On the other hand, even when the polyimide precursor compositionaccording to the exemplary embodiment has any configuration of thefollowings 1) to 3), the increase of the viscosity with the lapse oftime is prevented and excellent storage stability is exhibited.

1) Configuration in which the content (solid content) of a polyimideprecursor is increased (for example, configuration in which the contentof the polyimide precursor is set to be from 10% by weight to 50% byweight with respect to the polyimide precursor composition).

2) Configuration in which the weight average molecular weight of thepolyimide precursor is increased (for example, configuration in whichthe weight average molecular weight of the polyimide precursor is set tobe from 50,000 to 200,000).

3) Configuration in which an aromatic polyimide precursor is used as thepolyimide precursor (for example, configuration in which a condensationpolymer which is a condensation polymer of an aromatic tetracarboxylicdianhydride and an aromatic diamine compound and has a terminal sealedby a compound which includes not only the group having a triple bond,but also a carboxy group or an amino group is used as the polyimideprecursor).

Generally, in the case where the aromatic polyimide precursor(condensation polymer of an aromatic tetracarboxylic dianhydride and anaromatic diamine compound), there is a tendency of having difficulty inbeing dissolved in the aqueous solvent.

However, in the polyimide precursor composition according to theexemplary embodiment, since the group having a triple bond is providedat a terminal thereof, solubility of the specific polyimide precursor inthe aqueous solvent is improved. Therefore, even in the case where anaromatic polyimide precursor is used as the specific polyimideprecursor, the storage stability is excellent.

In the polyimide precursor composition according to the exemplaryembodiment, an aqueous solvent including water is used as the solvent.Therefore, the polyimide precursor composition according to theexemplary embodiment has excellent environmental aptitude. When apolyimide molded article is molded by using the polyimide precursorcomposition according to the exemplary embodiment, a decrease of aheating temperature for distilling the solvent and reduction of aheating time are exhibited.

In the polyimide precursor according to the exemplary embodiment, it ispreferable that an organic amine compound is further dissolved in theaqueous solvent.

If the organic amine compound is dissolved in the aqueous solvent, thespecific polyimide precursor (carboxy group provided at a position otherthan the terminal thereof) turns into a state of becoming an amine saltby the organic amine compound, and thus solubility of the specificpolyimide precursor in the aqueous solvent is further improved.Therefore, storage stability of the polyimide precursor composition isfurther improved.

In addition, if the organic amine compound is dissolved in the aqueoussolvent, corrosion of a base as a ground when the polyimide moldedarticle is molded is prevented. It is considered that the reason isbecause exhibition of acidity of the carboxy group in the specificpolyimide precursor is prevented by basicity of the organic aminecompound.

Hereinafter, components of the polyimide precursor composition accordingto this exemplary embodiment will be described.

Specific Polyimide Precursor

The specific polyimide precursor is a polyimide precursor in which agroup having a triple bond is provided at a terminal thereof.Specifically, for example, the specific polyimide precursor is a resin(polyamic acid) having a repetitive unit represented by formula (I) andis a resin in which a group having a triple bond is provided at aterminal thereof.

The resin (polyamic acid) having a repetitive unit represented byformula (I) is not a low molecule compound and does not have a structurein which an interaction force between polymer chains is decreased byintroducing a flexion chain, an aliphatic cyclic structure, and the liketo a primary structure, so as to improve solubility in a solvent. In theresin, the solubility of the polyimide precursor in the aqueous solventis improved by introducing the group having a triple bond to a terminalthereof. Therefore, depolymerization of a polyimide precursor shown in amethod of improving solubility and deterioration of mechanical strengthof a polyimide molded article, which may occur on changing a molecularstructure of the polyimide precursor in a polyimide precursor resin inthe related art, are not caused. In addition, water solubility of thepolyimide precursor is improved.

(In formula (I), A represents a tetravalent organic group and Brepresents a bivalent organic group.)

Here, in formula (I), the tetravalent organic group represented by A maybe a residual group obtained by removing four carboxy groups fromtetracarboxylic dianhydride which is a raw material.

The bivalent organic group represented by B may be a residual groupobtained by removing two amino groups from a diamine compound which is araw material.

That is, the specific polyimide precursor having a repetitive unitrepresented by formula (I) is a condensation polymer of thetetracarboxylic dianhydride and the diamine compound.

The tetracarboxylic dianhydride may be an aromatic compound or analiphatic compound, and however, the aromatic compound is preferablyused as the tetracarboxylic dianhydride. That is, a tetravalent organicgroup represented by A in formula (I) is preferably an aromatic organicgroup.

Examples of the aromatic tetracarboxylic dianhydride includepyromelletic dianhydride, 3,3′,4,4′-benzophenone tetracarboxylicdianhydride, 3,3′,4,4′-biphenyl sulfone tetracarboxylic dianhydride,1,4,5,8-naphthalene tetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 3,3′,4,4′-biphenyl ether tetracarboxylicdianhydride, 3,3′,4,4′-dimethyl-diphenyl silane tetracarboxylicdianhydride, 3,3′,4,4′-tetra phenylsilane tetracarboxylic dianhydride,1,2,3,4-furan tetracarboxylic dianhydride, 4,4′-bis(3,4-dicarboxyphenoxy)diphenyl sulfide dianhydride, 4,4′-bis(3,4-dicarboxyphenoxy)diphenylsulfonedianhydride, 4,4′-bis(3,4-dicarboxyphenoxy)diphenyl propane dianhydride, 3,3′,4,4′-perfluoroisopropylidenediphthalic dianhydride, 3,3′,4,4′-biphenyl tetracarboxylicdianhydride, 2,3,3′,4′-biphenyl tetracarboxylic dianhydride,bis(phthalic acid)phenylphosphine oxide dianhydride,p-phenylene-bis(triphenyl phthalic acid)dianhydride,m-phenylene-bis(triphenyl phthalic acid)dianhydride, bis(triphenylphthalic acid)-4,4′-diphenyl ether dianhydride, bis(triphenyl phthalicacid)-4,4′-diphenylmethane dianhydride.

Examples of aliphatic tetracarboxylic dianhydride include aliphatic oralicyclic tetracarboxylic dianhydride such as butane tetracarboxylicdianhydride, 1,2,3,4-cyclobutane tetracarboxylic dianhydride,1,3-dimethyl-1,2,3,4-cyclobutane tetracarboxylic dianhydride,1,2,3,4-cyclopentane tetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentyl acetic dianhydride, 3,5,6-tricarboxy norbornane-2-aceticacid dianhydride, 2,3,4,5-tetrahydrofuran tetracarboxylic dianhydride,5-(2,5-di-oxo-tetrahydrofuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylicacid dianhydride, bicyclo[2,2,2]-oct-7-ene-2,3,5,6-tetracarboxylicdianhydride; aliphatic tetracarboxylic dianhydride having an aromaticring, such as1,3,3a,4,5,9b-hexahydro-2,5-dioxo-3-furanyl)-naphtho[1,2-c]furan-1,3-dione,1,3,3a,4,5,9b-hexahydro-5-methyl-5-(tetrahydro-2,5-dioxo-3-furanyl)-naphtho[1,2-c]furan-1,3-dione,and1,3,3a,4,5,9b-hexahydro-8-methyl-5-(tetrahydro-2,5-dioxo-3-furanyl)-naphtho[1,2-c]furan-1,3-dione.

Among these substances, an aromatic tetracarboxylic dianhydride may beused as tetracarboxylic dianhydride. Specifically, for example,pyromelletic dianhydride, 3,3′,4,4′-biphenyl tetracarboxylicdianhydride, 2,3,3′,4′-biphenyl tetracarboxylic dianhydride,3,3′,4,4′-biphenyl ether tetracarboxylic dianhydride, and3,3′,4,4′-benzophenone tetracarboxylic dianhydride may be used.Pyromelletic dianhydride, 3,3′,4,4′-biphenyl tetracarboxylicdianhydride, and 3,3′,4,4′-benzophenone tetracarboxylic dianhydride maybe further used. 3,3′,4,4′-biphenyl tetracarboxylic dianhydride may beparticularly used.

One type of tetracarboxylic dianhydride may be used singly orcombination of two or more types of tetracarboxylic dianhydride may beused together.

When combination of two or more types of tetracarboxylic dianhydride isused together, an aromatic tetracarboxylic dianhydride or an aliphatictetracarboxylic dianhydride may be used, or an aromatic tetracarboxylicdianhydride and an aliphatic tetracarboxylic dianhydride may be used incombination.

The diamine compound is a diamine compound having two amino groups in amolecular structure, and may be aromatic or aliphatic. However, anaromatic compound may be preferably used. That is, the bivalent organicgroup represented by B in formula (I) may be an aromatic organic group.

Examples of the diamine compound include an aromatic diamine such asp-phenylenediamine, m-phenylenediamine, 4,4′-diaminodiphenylmethane,4,4′-diaminodiphenyl ethane, 4,4′-diaminodiphenyl ether,4,4′-diaminodiphenyl sulfide, 4,4′-diamino-diphenyl sulfone,1,5-diamino-naphthalene, 3,3-dimethyl-4,4′-diamino biphenyl,5-amino-1-(4′-amino phenyl)-1,3,3-trimethyl-indane, 6-amino-1-(4′-aminophenyl)-1,3,3-trimethyl-indane, 4,4′-diamino benzanilide,3,5-diamino-3′-trifluoromethyl benzanilide,3,5-diamino-4′-trifluoromethyl benzanilide, 3,4′-diaminodiphenyl ether,2,7-diamino-fluorene, 2,2-bis(4-aminophenyl) hexafluoropropane,4,4′-methylene-bis(2-chloroaniline), 2,2′,5,5′-tetrachloro-4,4′-diaminobiphenyl, 2,2′-dichloro-4,4′-diamino-5,5′-dimethoxy biphenyl,3,3′-dimethoxy-4,4′-diamino biphenyl,4,4′-diamino-2,2′-bis(trifluoromethyl) biphenyl,2,2-bis[4-(4-aminophenoxy)phenyl]propane,2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane,1,4-bis(4-aminophenoxy)benzene, 4,4′-bis(4-aminophenoxy)-biphenyl,1,3′-bis(4-aminophenoxy)benzene, 9,9-bis(4-aminophenyl)fluorene,4,4′-(p-phenylene isopropylidene)bisaniline, 4,4′-(m-phenyleneisopropylidene)bisaniline,2,2′-bis[4-(4-amino-2-trifluoromethylphenoxy)phenyl]hexafluoropropane,and 4,4′-bis[4-(4-amino-2-trifluoromethyl)phenoxy]-octafluorobiphenyl;aromatic diamine such as diaminotetraphenyl thiophene, which has twoamino groups bonded to an aromatic ring and hetero atoms other than anitrogen atom of the amino group; aliphatic diamine and alicyclicdiamine such as 1,1-metaxylylene diamine, 1,3-propane diamine,tetramethylene diamine, pentamethylene diamine, octamethylene diamine,nonamethylene diamine, 4,4-diamino heptamethylene diamine, 1,4-diaminocyclohexane, isophorone diamine, tetrahydrodicyclopentadienylenediamine, hexahydro-4,7-metanoindanylene dimethylene diamine, andtrycyclo[6,2,1,0^(2.7)]-undecylene dimethyl diamine, and4,4′-methylenebis(cyclohexylamine).

Among these substances, the aromatic diamine compound may be used as thediamine compound. Specifically, for example, p-phenylenediamine,m-phenylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylether, 3,4′-diaminodiphenyl ether, 4,4′-diaminodiphenyl sulfide, and4,4′-diaminodiphenyl sulfone may be used. 4,4′-diaminodiphenyl ether andp-phenylenediamine may be particularly used.

One of the diamine compounds may be used singly or two or more of thediamine compounds may be used in combination. When two or more of thediamine compounds are used in combination, two or more of the aromaticdiamine compounds or two or more of the aliphatic diamine compounds maybe used, or the aromatic diamine compound and the aliphatic diaminecompound may be used in combination.

The specific polyimide precursor may be a resin having an imidizationrate of 0.2 or less. That is, the specific polyimide precursor may be aresin being partially imidized.

Specific examples of the specific polyimide precursor include a resinhaving repetitive units represented by formula (I-1), formula (I-2), andformula (I-3).

In the formula (I-1), the formula (I-2), and the formula (I-3), Arepresents a tetravalent organic group and B represents a bivalentorganic group. A and B have the same meanings as those of A and B informula (I), respectively.

l represents an integer of 1 or greater. m and n each represent aninteger of 0 or greater. l, m, and n satisfy a relationship of(2n+m)/(2l+2m+2n)≤0.2.

In formulas (I-1) to (I-3), l represents an integer of 1 or greater,preferably an integer of 1 to 200, and more preferably an integer of 1to 100. m and n each represent an integer of 0 or greater, preferablyfrom 0 to 200, and more preferably from 0 to 100.

l, m, and n satisfy a relationship of (2n+m)/(2l+2m+2n)≤0.2, preferablysatisfy a relationship of (2n+m)/(2l+2m+2n)≤0.15, and more preferablysatisfy a relationship of (2n+m)/(2l+2m+2n)≤0.10.

Here, “(2n+m)/(2l+2m+2n)” represents a ratio of the number of bondingparts (2n+m) subjected to imide ring closure, to the number of allbonding parts (2l+2m+2n) among bonding parts (reaction parts oftetracarboxylic dianhydride and the diamine compound) of the specificpolyimide precursor. That is, “(2n+m)/(2l+2m+2n)” represents animidization rate of the specific polyimide precursor.

Accordingly, if the imidization rate (value of “(2n+m)/(2l+2m+2n)”) ofthe specific polyimide precursor is set to 0.2 or less (preferably 0.15or less and more preferably 0.10 or less), gelling or precipitating andseparating of the specific polyimide precursor is prevented.

The imidization rate (value of “(2n+m)/(2l+2m+2n)”) of the specificpolyimide precursor is measured by the following method.

Measurement of Imidization Rate of Polyimide Precursor

Preparation of Polyimide Precursor Sample

(i) A silicone wafer is coated with a polyimide precursor composition tobe measured so as to have a film thickness of a range of 1 μm to 10 μm,thereby preparing a coated film sample.

(ii) The coated film sample is immersed in tetrahydrofuran (THF) for 20minutes and a solvent in the coated film sample is exchanged withtetrahydrofuran (THF). The immersed solvent is not limited to THF. Asolvent which does not dissolve the polyimide precursor and may be mixedwith a solvent component included in the polyimide precursor compositionmay be selected. Specifically, an alcohol solvent such as methanol andethanol, and an ether compound such as dioxane may be used.

(iii) The coated film sample is taken out from THF, and THF adhering tothe surface of the coated film sample is removed by spraying N₂ gas tothe THF. The coated film sample is dried by performing treatment underreduced pressure of 10 mmHg or smaller at a temperature range of 5° C.to 25° C. for 12 hours or longer, and thereby a polyimide precursorsample is prepared.

Preparation of 100% Imidized Standard Sample

(iv) Similarly to the (i), a silicone wafer is coated with a polyimideprecursor composition to be measured and thereby a coated film sample isprepared.

(v) An imidization reaction is performed by heating the coated filmsample at 380° C. for 60 minutes, and thereby a 100% imidized standardsample is prepared.

Measurement and Analysis (Measurement Example and Analysis Example ofPolyimide Precursor Sample formed of 4,4′-diaminodiphenyl ether and3,3′,4,4′-biphenyl tetracarboxylic dianhydride)

(vi) Infrared absorption spectra of the 100% imidized standard sampleand the polyimide precursor sample are measured by a Fourier transforminfrared spectrophotometer (FT-730 manufactured by HORIBA, Ltd.). Aratio I′ (100) of an absorption peak (Ab′ (1780 cm⁻¹)) derived fromimide bonds in the vicinity of 1780 cm⁻¹ to an absorption peak (Ab′(1500 cm⁻¹)) derived from an aromatic ring in the vicinity of 1500 cm⁻¹of the 100% imidized standard sample is obtained.

(vii) The polyimide precursor sample is measured in a similar manner,and thus a ratio I(x) of an absorption peak (Ab (1780 cm⁻¹)) derivedfrom imide bonds in the vicinity of 1780 cm⁻¹ to an absorption peak(Ab(1500 cm⁻¹)) derived from an aromatic ring in the vicinity of 1500cm⁻¹ is obtained.

An imidization rate of the polyimide precursor is calculated based onthe following expressions by using the measured ratios I′ (100) andI(x).imidization rate of polyimide precursor I(x)/I′(100)  Expression:I′(100)=(Ab′(1780 cm⁻¹))/(Ab′(1500 cm⁻¹))  Expression:I(x)=(Ab(1780 cm⁻¹))/(Ab(1500 cm⁻¹))  Expression:

Measurement of the imidization rate of this polyimide precursor isapplied to measurement of an imidization rate of an aromatic polyimideprecursor. When an imidization rate of an aliphatic polyimide precursoris measured, a peak derived from a structure which is not changed beforeand after the imidization reaction is used as an internal standard peak,instead of an absorption peak of the aromatic ring.

Ratio of Tetracarboxylic Dianhydride and Diamine Compound

In the specific polyimide precursor, the molar equivalent number of thediamine compound is preferably greater than the molar equivalent numberof tetracarboxylic dianhydride. If this relation is satisfied, storagestability is easily improved. In addition, mechanical strength of apolyimide molded article is also easily improved.

The molar equivalent of the diamine compound used during apolymerization reaction is set excessive with respect to the molarequivalent of tetracarboxylic dianhydride in order to realize the aboverelation. The ratio between the molar equivalents of the diaminecompound and the tetracarboxylic dianhydride is a value of the molarequivalent of the diamine compound taking the molar equivalent oftetracarboxylic dianhydride as 1. This ratio is preferably from 1.0001to 1.2000, and more preferably from 1.0010 to 1.2000.

If the ratio between the molar equivalents of the diamine compound andthe tetracarboxylic dianhydride is equal to or greater than 1.0001, whenthe content ratio of the number of the group having a triple bond to thenumber of all the terminals is smaller than 100 mol %, an amino group isprovided as a terminal group other than the group having a triple bond,at a molecular terminal. Therefore, dispersibility of the specificpolyimide precursor is improved and storage stability is easilyimproved, by an action of the amino group at the molecular terminal, ascompared with the case where a carboxy group is provided at themolecular terminal. In addition, film preparation properties of apolyimide precursor composition are easily improved. Mechanical strengthof a polyimide molded article is easily improved. Further, dispersion ofvarious fillers added for applying various functions to the polyimidemolded article is enhanced, and the high function is easily expressedeven when the filler is used in a small amount, as compared with thecase where a carboxy group is provided at the molecular terminal. If theratio for the molar equivalent is equal to or smaller than 1.2000, themolecular weight of the polyimide precursor is easily increased. Forexample, when a film-shaped polyimide molded article is used, filmstrength (tensile breaking strength and tensile elongation at break) ofthe film-shaped polyimide molded article is easily obtained.

Here, the molar equivalent of the diamine compound and the molarequivalent of tetracarboxylic dianhydride in the specific polyimideprecursor are measured as follows. The specific polyimide precursorresin is decomposed into a diamine compound and a tetracarboxylic acidsalt by performing hydrolysis treatment in a basic aqueous solution suchas sodium hydroxide and potassium hydroxide. The obtained sample isanalyzed according to gas chromatography or liquid chromatography, andthus a ratio of tetracarboxylic dianhydride and the diamine compoundconstituting the specific polyimide precursor is determined.

Terminal Structure of Polyimide Precursor

The group having a triple bond is provided at a terminal (that is, amolecular terminal) of the specific polyimide precursor.

As a method of introducing the group having a triple bond to a terminalof the specific polyimide precursor, a method of sealing a terminal of acondensation polymer of tetracarboxylic dianhydride and a diaminecompound with a compound having not only a group having a triple bondbut also a carboxy group or an amino group is exemplified. That is, acondensation polymer which is a condensation polymer of tetracarboxylicdianhydride (preferably aromatic tetracarboxylic dianhydride) and adiamine compound (preferably aromatic diamine compound) and has aterminal sealed by a compound having not only the group having a triplebond but also a carboxy group or an amino group is exemplified as thespecific polyimide precursor.

Here, the compound which has not only the group having a triple bond butalso a carboxy group or an amino group (also referred to as “anacetylene compound” below) may have plural groups having the triplebonds or may have plural carboxy groups or plural amino groups. Theplural carboxy groups may be subjected to anhydride.

As the group having a triple bond, an alkynyl group (alkynyl grouphaving 2 to 10 carbon atoms, such as an ethynyl group (acetylene group),a propynyl group, and a phenylethynyl group) is exemplified.

As the acetylene compound, dicarboxylic anhydride which includes thegroup having a triple bond and a monoamine compound which includes thegroup having a triple bond are exemplified.

As the dicarboxylic anhydride which includes the group having a triplebond, ethynylphthalic anhydride, propynylphthalic anhydride, andphenylethynyl phthalic anhydride are exemplified.

As the monoamine compound which includes the group having a triple bond,ethynylamine, ethynylaniline, propynylaniline, and phenylethynylanilineare exemplified.

Among the substances, from a viewpoint of the storage stability,dicarboxylic anhydride which includes the group having a triple bond anda monoamine compound which includes the group having a triple bond arepreferable as the acetylene compound. Ethynylphthalic anhydride,ethynylamine, and ethynylaniline are more preferable.

Regarding introduction of the group having a triple bond to the terminalof the specific polyimide precursor, in the case where the molarequivalent of the diamine compound is greater than the molar equivalentof the tetracarboxylic dianhydride in performing condensationpolymerization of a tetracarboxylic dianhydride and a diamine compound,the compound which includes the group having a triple bond and a carboxygroup is used as the acetylene compound. In the case where the molarequivalent of the tetracarboxylic dianhydride is greater than the molarequivalent of the diamine compound, the compound which includes thegroup having a triple bond and an amino group is used as the acetylenecompound.

The ratio (also referred to as “the quantity of the terminal acetylenegroup) of the number of the group having a triple bond to the number ofall of the terminals in the specific polyimide precursor is preferablyfrom 90 mol % to 100 mol %, and more preferably from 95 mol % to 100 mol%.

If the quantity of the terminal acetylene group is in the above range,the storage stability is easily improved.

The quantity of the terminal acetylene group is measured byquantification of a nuclear magnetic resonance (NMR) method.Specifically, the quantity of the terminal acetylene group is measuredas follows.

When a molar ratio (terminal acetylene group/specific polyimideprecursor) between the terminal acetylene group and the specificpolyimide precursor, which is measured by NMR, is designated as asealing ratio A (mol %), a weight ratio thereof (that is, quantity ofthe terminal acetylene group) X is represented by the followingexpression.X=[2×M _((X)) ×A/100]/M _((PAA))

In the expression, M_((X)) represents a molecular weight of the terminalacetylene group, M_((PAA)) represents a molecular weight (value of thenumber average molecular weight of GPC) of the specific polyimideprecursor, and A represents a sealing ratio (mol %).

Weight Average Molecular Weight of Polyimide Precursor

The weight average molecular weight of the specific polyimide precursormay be from 2,000 to 200,000, preferably is from 50,000 to 200,000, morepreferably from 5,000 to 100,000, and particularly preferably from10,000 to 70,000.

In particular, even though the weight average molecular weight of thespecific polyimide precursor is increased to be from 50,000 to 200,000in order to form a polyimide precursor composition having highmechanical characteristics such as tensile breaking strength and tensileelongation at break, the storage stability is improved.

The ratio between the molar equivalents of the tetracarboxylicdianhydride and the diamine compound is adjusted such that a polyimideprecursor having a desired weight average molecular weight is obtained.

The weight average molecular weight of the specific polyimide precursoris measured according to a gel permeation chromatography (GPC) methodunder the following measurement conditions.

-   -   Column: TSKgelα-M manufactured by Tosoh Corporation (7.8 mm        I.D×30 cm)    -   Eluent: DMF (dimethylformamide)/30 mM LiBr/60 mM phosphoric acid    -   Flow speed: 0.6 mL/min    -   Injection volume: 60 μL    -   Detector: RI (differential refractive index detector)

A content (concentration) of the polyimide precursor may be from 0.1% byweight to 50% by weight with respect to the polyimide precursorcomposition, preferably from 0.5% by weight to 25% by weight, and morepreferably from 1% by weight to 20% by weight.

In particular, even though the content of the polyimide precursor isincreased to be from 10% by weight to 50% by weight with respect to thepolyimide precursor composition in order to form a polyimide precursorcomposition being high in mechanical characteristics such as tensilebreaking strength and tensile elongation at break, the storage stabilityis improved.

Organic Amine Compound

The organic amine compound is a compound that improves solubility of thespecific polyimide precursor in the solvent by causing the specificpolyimide precursor (carboxy group thereof) to become an amine salt andfunctions as an imidization accelerator. The organic amine compound is asurface-inactive amine compound which does not have surface activity.Specifically, the organic amine compound may be an amine compound havinga molecular weight which is equal to or smaller than 170. The organicamine compound may be a compound except for the diamine compound whichis the raw material of the polyimide precursor.

The organic amine compound may be a water-soluble compound. Here, “watersolubility” means that 1% by weight or greater of a target substance isdissolved in water at 25° C.

As the organic amine compound, a primary amine compound, a secondaryamine compound, and a tertiary amine compound are exemplified.

Among the compounds, at least one (particularly, tertiary aminecompound) selected from the secondary amine compound and the tertiaryamine compound may be used as the organic amine compound. When thetertiary amine compound or the secondary amine compound (particularly,tertiary amine compound) is used as the organic amine compound,solubility of the specific polyimide precursor in the solvent isimproved and the storage stability of the polyimide precursorcomposition is easily improved.

A bivalent or higher polyvalent amine compound in addition to amonovalent amine compound is also exemplified as the organic aminecompound. If the bivalent or higher polyvalent amine compound is used, apseudo-crosslinking structure is easily formed between molecules of thespecific polyimide precursor, and the storage stability of the polyimideprecursor composition is easily improved.

Examples of the primary amine compound include methylamine, ethylamine,n-propylamine, isopropylamine, 2-ethanolamine, and2-amino-2-methyl-1-propanol.

Examples of the secondary amine compound include dimethylamine,2-(methylamino)ethanol, 2-(ethylamino)ethanol, and morpholine.

Examples of the tertiary amine compound include 2-dimethyl aminoethanol,2-diethyl aminoethanol, 2-dimethyl aminopropanol, triethylamine,picoline, methylmorpholine, and ethylmorpholine.

Here, from a viewpoint of the storage stability, an amine compound(particularly, tertiary amine compound) having a heterocyclic structurewhich contains nitrogen is also preferable as the organic aminecompound. Examples of the amine compound having a heterocyclic structurewhich contains nitrogen (referred to as “a nitrogen-containingheterocyclic amine compound” below) include isoquinolines (aminecompound having an isoquinoline skeleton), pyridines (amine compoundhaving a pyridine skeleton), pyrimidines (amine compound having apyrimidine skeleton), pyrazines (amine compound having a pyrazineskeleton), piperazines (amine compound having a piperazine skeleton),triazines (amine compound having a triazine skeleton), imidazoles (aminecompound having an imidazole skeleton), polyaniline, polypyridine, andpolyamine.

As the organic amine compound, from a viewpoint of the storagestability, at least one selected from the group consisting ofmorpholines, amino alcohols, and imidazoles is preferable, and at leastone selected from the group consisting of N-methylmorpholine,N-ethylmorpholine, and dimethylaminoethanol is more preferable.

Among the above substances, a compound having a boiling point which isequal to or higher than 60° C. (preferably from 60° C. to 200° C. andmore preferably from 70° C. to 150° C.) may be used as the organic aminecompound. If the boiling point of the organic amine compound is set tobe equal to or higher than 60° C., an occurrence of a situation in whichthe organic amine compound is volatilized from the polyimide precursorcomposition when being stored is prevented. In addition, deteriorationof solubility of the specific polyimide precursor in the solvent iseasily prevented.

The content of the organic amine compound may be from 30 mol % to 200mol % (preferably from 50 mol % to 150 mol %, and more preferably from80 mol % to 120 mol %) with respect to a carboxy group (—COOH) of thepolyimide precursor in the polyimide precursor composition. If thecontent of the organic amine compound is set to be equal to or greaterthan 50 mol %, the polyimide precursor is easily dissolved in theaqueous solvent. If the content of the organic amine compound is set tobe equal to or smaller than 200 mol %, stability of the organic aminecompound in the solution is easily ensured and an unpleasant odor isalso prevented.

One type of the organic amine compound may be singly used or combinationof two types thereof may be used.

Aqueous Solvent

The aqueous solvent is a solvent including water. Specifically, theaqueous solvent may be a solvent which includes 10% by weight or greaterof water with respect to the entirety of the aqueous solvent. Here,“water solubility” means that 1% by weight or greater of a targetsubstance is dissolved in water at 25° C.

Examples of water include distilled water, ion exchange water,ultrafiltration water, and pure water.

The content of water is preferably from 50% by weight to 100% by weight,more preferably from 70% by weight to 100% by weight, further preferablyfrom 80% by weight to 100% by weight, and particularly preferably from90% by weight to 100% by weight, with respect to the entirety of theaqueous solvent. It is most preferable that the aqueous solvent does notinclude a solvent other than water.

In the case where the aqueous solvent includes a solvent other thanwater, examples of the solvent other than water include a water-solubleorganic solvent and an aprotic polar solvent. From a viewpoint oftransparency, mechanical strength of a polyimide molded article, thewater-soluble organic solvent is preferable as the solvent other thanwater. In particular, from a viewpoint of improving variouscharacteristics of a polyimide molded article, such as heat resistance,an electrical characteristic, and solvent resistance in addition tomechanical strength, it is preferable that the aqueous solvent does notinclude an aprotic polar solvent or includes an aprotic polar solvent ina small amount (for example, 10% by weight or smaller with respect tothe entirety of a water-soluble solvent).

Examples of the water-soluble organic solvent include a water-solubleether solvent, a water-soluble ketone solvent, and a water-solublealcohol solvent.

One type of the water-soluble organic solvent may be singly used.However, in the case where combination of two types thereof is used,examples of the combination include combination of a water-soluble ethersolvent and a water-soluble alcohol solvent, combination of awater-soluble ketone solvent and a water-soluble alcohol solvent, andcombination of a water-soluble ether solvent, a water-soluble ketonesolvent, and a water-soluble alcohol solvent.

The water-soluble ether solvent is a water-soluble solvent which has anether bond in one molecule. Examples of the water-soluble ether solventinclude tetrahydrofuran (THF), dioxane, trioxane, 1,2-dimethoxyethane,diethylene glycol dimethyl ether, and diethylene glycol diethyl ether.Among the above substances, tetrahydrofuran and dioxane are preferableas the water-soluble ether solvent.

The water-soluble ketone solvent is a water-soluble solvent which has aketone group in one molecule. Examples of the water-soluble ketonesolvent include acetone, methyl ethyl ketone, and cyclohexanone. Amongthe above substances, acetone is preferable as the water-soluble ketonesolvent.

The water-soluble alcohol solvent is a water-soluble solvent which hasan alcoholic hydroxyl group in one molecule. Examples of thewater-soluble alcohol solvent include methanol, ethanol, 1-propanol,2-propanol, tert-butyl alcohol, ethylene glycol, monoalkyl ether ofethylene glycol, propylene glycol, monoalkyl ether of propylene glycol,diethylene glycol, monoalkyl ether of diethylene glycol,1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol,2,3-butanediol, 1,5-pentanediol, 2-butene-1,4-diol,2-methyl-2,4-pentanediol, glycerin,2-ethyl-2-hydroxymethyl-1,3-propanediol, and 1,2,6-hexanetriol. Amongthe above substances, methanol, ethanol, 2-propanol, ethylene glycol,monoalkyl ether of ethylene glycol, propylene glycol, monoalkyl ether ofpropylene glycol, diethylene glycol, and monoalkyl ether of diethyleneglycol are preferable as the water-soluble alcohol solvent.

The aprotic polar solvent is a solvent which has a boiling point of 150°C. to 300° C. and a dipole moment of 3.0 D to 5.0 D. Specific examplesof the aprotic polar solvent include N-methyl-2-pyrrolidone (NMP),N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), dimethylsulfoxide (DMSO), hexamethylenephosphoramide (HMPA), N-methylcaprolactam, and N-acetyl-2-pyrrolidone.

In the case where the solvent other than water is contained as theaqueous solvent, a solvent which is used together may have a boilingpoint which is equal to or lower than 250° C., preferably from 60° C. to200° C., and more preferably from 80° C. to 150° C. When the boilingpoint of the solvent used together is set to be in the above range, thesolvent other than water is unlikely to remain on a polyimide moldedarticle and a polyimide molded article having high mechanical strengthis easily obtained.

Other Additives

The polyimide precursor composition according to the exemplaryembodiment may include various fillers for imparting various functionssuch as conductivity and mechanical strength to a polyimide moldedarticle prepared by the polyimide precursor composition. Furthermore,the polyimide precursor composition may include a catalyst foraccelerating the imidization reaction, a leveling material for improvingquality of a prepared film, or the like.

Example of a conductive material which is added for impartingconductivity include a material being conductive (for example, volumeresistivity being less than 10⁷ Ω·cm, this is hereinafter applied) or amaterial being semiconductive (for example, volume resistivity beingfrom 10⁷ Ω·cm to 10¹³ Ω·cm, this is hereinafter applied). Theseconductive materials are selected in accordance with a use purpose.

Example of the conductive material include carbon black (for example,acidic carbon black being equal to or less than pH 5.0), metal (forexample, aluminum, and nickel), metal oxide (for example, yttrium oxide,and tin oxide), anion conductive material (for example, potassiumtitanate, and LiCl), and a conductive polymer (for example, polyaniline,polypyrrole, polysulfone, and polyacetylene).

One of the conductive material may be singly used or two or more thereofmay be used in combination.

When the conductive material has a particle shape, the conductivematerial may be particles preferably having a primary particle size ofless than 10 μm, and more preferably having a primary particle size of 1μm or less.

Examples of the filler which is added for improving the mechanicalstrength includes a particle-shaped material such as silica powder,alumina powder, barium sulfate powder, titanium oxide powder, mica, andtalc. Furthermore, powder of a fluorine resin such as polytetrafluoroethylene (PTFE) and tetrafluoroethylene perfluoroalkyl vinyl ethercopolymer (PFA) may be added for improving water repellency and releaseproperties on the surface of the polyimide molded article.

As the catalyst for accelerating the imidization reaction, a dehydratingagent, such as acidic anhydride, and an acidic catalyst such as a phenolderivative, a sulfonic acid derivative, and a benzoic acid derivative,may be used.

The content of the other additives may be selected in accordance with ause purpose of the prepared polyimide molded article.

Preparing Method of Polyimide Precursor Composition

A preparing method of the polyimide precursor composition according tothe exemplary embodiment is not particularly limited. For example, atetracarboxylic dianhydride, a diamine compound, and an acetylenecompound are polymerized in an aqueous solvent including water, so as toprepare a specific polyimide precursor in which the group having atriple bond is provided at a terminal thereof.

In the preparing method of the polyimide precursor composition accordingto the exemplary embodiment, it is preferable that the specificpolyimide precursor is produced in the presence of an organic aminecompound.

In the preparing method described herein, if necessary, a process ofsubstituting a solvent or changing a solvent composition may be providedafter the polymerization process.

Polyimide Molded Article and Preparing Method Thereof

The preparing method of a polyimide molded article according to theexemplary embodiment is a preparing method which includes subjecting thepolyimide precursor composition according to the exemplary embodiment(also hereinafter referred to as “a specific polyimide precursorcomposition”) to a heat treatment to perform molding.

Specifically, the preparing method of a polyimide molded articleaccording to the exemplary embodiment includes, for example, a processof forming a coated film by applying the specific polyimide precursorcomposition onto a coating target (referred to as “a coated-film formingprocess” below) and a process of forming a polyimide resin layer byheating the coated film (referred to as “a heating process” below).

Coated-film Forming Process

Firstly, a coating target (an object to be coated with the specificpolyimide precursor composition) is prepared. The coating target isselected in accordance with the use purpose of a polyimide moldedarticle to be prepared.

Specifically, in the case where a liquid crystal alignment film isprepared as the polyimide molded article, various substrates to beapplied to a liquid crystal element are exemplified as the coatingtarget. For example, a silicon substrate, a glass substrate, and asubstrate in which a metal or metal alloy film is formed on a surface ofeach of the forgoing substrates are exemplified.

In the case where a passivation film is prepared as the polyimide moldedarticle, for example, the coating target is selected from asemiconductor substrate on which an integrated circuit is formed, awiring substrate on which wiring is formed, a printed board on which anelectronic component and a wiring are provided, and the like.

In the case where a wire shell material is prepared as the polyimidemolded article, for example, various wires (wire material, bar material,or plate material made of metal or alloys such as soft copper, hardcopper, oxygen-free copper, chromium ore, and aluminum) are exemplifiedas the coating target. In the case where the polyimide molded article isformed and processed so as to have a tape shape and is used as a wireshell material which has a tape shape and is used for being wound arounda wire, various flat substrates or various cylindrical substrates areused as the coating target.

In the case where an adhesive film is prepared as the polyimide moldedarticle, for example, various molded articles which function as anadhering target (for example, various electrical components such as asemiconductor chip and a printed board) are exemplified.

Then, the desired coating target is coated with the specific polyimideprecursor composition, thereby forming a coated film of the specificpolyimide precursor composition.

A coating method of the specific polyimide precursor composition is notparticularly limited. For example, various coating methods such as spraycoating, a spin coating method, a roll coating method, a bar coatingmethod, a slit die coating method, and an ink jet coating method areexemplified.

Heating Process

Then, drying is performed on the coated film of the specific polyimideprecursor composition. A dry film (dried coated film before imidization)is formed by this drying treatment.

Regarding a heating condition for the drying treatment, the dryingtreatment may be performed, for example, at a temperature of 80° C. to200° C. for a period of 10 minutes to 60 minutes. As the temperature isincreased, a heating time may be reduced. Exposure to hot wind iseffective in the heating. In the heating, the temperature may be slowlyincreased or may be increased without changing a speed thereof.

Then, an imidization treatment is performed on the dry film. Thus, apolyimide resin layer is formed.

Heating conditions of the imidization treatment are a temperature of150° C. to 400° C. (preferably 200° C. to 300° C.) and a period of timeof 20 minutes to 60 minutes, for example. Heating under the aboveheating conditions causes the imidization reaction, and thereby apolyimide resin layer is formed. Before the temperature reaches thefinal temperature in heating process, heating may be performed at thetemperature which is increased stepwise or is slowly increased at aconstant speed, during a heating reaction.

A polyimide molded article is formed through the above-describedprocesses. If necessary, the polyimide molded article is detached fromthe coating target, and post-processing is performed.

Polyimide Molded Article

The polyimide molded article according to the exemplary embodiment is apolyimide molded article obtained by the preparing method of a polyimidemolded article according to the exemplary embodiment. Examples of thepolyimide molded article include various polyimide molded articles suchas a liquid crystal alignment film, a passivation film, a wire shellmaterial, and an adhesive film. In addition, examples of the polyimidemolded article include a flexible electronic substrate film, acopper-clad laminated film, a laminated film, an electric insulationfilm, a porous film for a fuel cell, a separation film, a heat-resistantcoated film, an IC package, a resist film, a flattening film, amicrolens array film, and an optical-fiber shell film.

As the polyimide molded article, a belt member is also exemplified. Asthe belt member, a driving belt, a belt (for example, an intermediatebelt, a transfer belt, a fixation belt, and a transporting transferbelt) for an electrophotographic image forming apparatus, and the likeare exemplified.

That is, the preparing method of the polyimide molded article accordingto the exemplary embodiment may be applied as a preparing method ofvarious polyimide molded articles described above.

An aqueous solvent included in the polyimide precursor composition iscontained in the polyimide molded article according to the exemplaryembodiment.

The content of the aqueous solvent contained in the polyimide moldedarticle according to the exemplary embodiment is 1 ppb or more and lessthan 1% with respect to the polyimide molded article. The quantity ofthe aqueous solvent contained in the polyimide molded article isdetermined in such a manner that a volume of a gas generated by heatingthe polyimide molded article is determined according to a gaschromatography method. The quantity of the organic amine compoundincluded in the polyimide molded article is also determined in such amanner that a volume of a gas generated by heating the polyimide moldedarticle is determined according to a gas chromatography method.

EXAMPLES

Hereinafter, examples will be described. However, the exemplaryembodiment of the invention is not limited to these examples. In thefollowing descriptions, all of “part” and “%” are based on a weightbasis, unless otherwise indicated.

Underwater Polymerization Method Example 1

Underwater Polymerization Method

Preparation of Polyimide Precursor Composition (A-1)

Polymerization Process

A flask equipped with a stirring rod, a thermometer, and a drippingfunnel is filled with 308 g of water as the aqueous solvent. 21.44 g(198.26 mmol) of p-phenylenediamine (PDA: molecular weight of 108.14) asthe diamine compound, 70.00 g (237.92 mmol) of 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA: molecular weight of 294.22) astetracarboxylic dianhydride, and 9.29 g (79.31 mmol) of 3-ethynylanilineas the acetylene compound are added to the flask. Then, the substancesare dispersed by performing stirring at 20° C. for 10 minutes. 48.13 g(475.83 mmol) of methyl morpholine (described as MMO below: organicamine compound) as the organic amine compound are added. Further,dissolution and a reaction are performed by performing stirring for 24hours while the flask is held at a reaction temperature of 50° C. Thus,a polyimide precursor composition (A-1) is obtained.

After the storage stability of the obtained polyimide precursorcomposition is evaluated, a film is prepared by using the polyimideprecursor composition, and film preparation properties of the preparedfilm are evaluated. The evaluation results are shown in Table 1 below.

Here, regarding the polyimide precursor composition (A-1) just afterbeing prepared, the quantity of the terminal acetylene group of apolyimide precursor, a solid content of the polyimide precursor (PIprecursor), an imidization rate of the polyimide precursor, themolecular weight (weight average molecular weight Mw) of the polyimideprecursor (PI precursor), a solid content as polyimide (polyimide solidcontent), a liquid state of the composition, and viscosity of thecomposition are measured.

The imidization rate of the produced polyimide precursor is 0.02. Thequantity of the terminal acetylene groups of the polyimide precursor ismeasured as described above. As a result, the polyimide precursor hasacetylene groups at all the terminals.

Various measurement methods (measurement method other than the methodsdescribed above) are as follows.

Viscosity Measuring Method

Viscosity is measured under the following conditions by means of an Etype viscometer.

-   -   Measuring device: E type rotation viscometer TV-20H (Toki Sangyo        Co., Ltd)    -   Measurement probe: No. 3 type rotor 3°×R14    -   Measurement temperature: 22° C.

Measurement Method of Polyimide Solid Content (PI Solid Content)

A polyimide solid content is measured under the following conditions byusing a differential heat-thermogravimetry simultaneous measurementdevice. The measured value at 380° C. is denoted as a polyimide solidcontent.

-   -   Measuring device: differential heat-thermogravimetry        simultaneous measurement device TG/DTA6200 (Seiko Instruments        Inc.)    -   Measurement range: from 20° C. to 400° C.    -   Temperature rising speed: 20° C./minute

Evaluation

The storage stability of the obtained polyimide precursor composition(A-1) is evaluated. Film preparing is performed by using the obtainedpolyimide precursor composition (A-1), thereby preparing a film. Filmpreparation properties of the prepared film are evaluated.

Storage Stability

The polyimide precursor composition (A-1) is stored at room temperature(25° C.) for 20 days, and then the liquid state of the composition, theviscosity of the composition, and the imidization rate of the polyimideprecursor (PI precursor) are measured. Evaluation criteria for theliquid state are as follows.

A: stringiness is not viewed

B: stringiness is slightly viewed (when a spatula is put and pulled by 1to 5 cm, the composition is not cut off).

C: stringiness is viewed (when a spatula is put and pulled by 5 to 20cm, the composition is not cut off).

D: stringiness is remarkably viewed (when a spatula is put and pulled by20 cm or greater, the composition is not cut off).

Film Preparation Properties

Film preparation is performed through the following operation by usingthe polyimide precursor composition (A-1) after being stored at roomtemperature (25° C.) for 20 days. Regarding a prepared film, (1) voidtrace and (2) surface unevenness and pattern are evaluated.

-   -   Coating method: bar coating method using a coating blade which        has a spacer installed thereon so as to cause the thickness        obtained by coating to be 100 μm.    -   Coating base: 1.1 mmt glass plate    -   Drying temperature: 60° C.×10 minutes    -   Firing temperature: 250° C.×30 minutes    -   (1) Void Trace

It is evaluated whether or not a void trace is provided on the surfaceof the prepared film. Evaluation criteria are as follows.

A: formation of a void trace is not recognized.

B: the number of the void traces confirmed on the surface of theprepared film is 1 or more and less than 10.

C: 10 or more and less than 50 of void traces are scattered on thesurface of the prepared film.

D: many void traces are uniformly formed on the surface of the preparedfilm.

(2) Surface Unevenness and Pattern

It is evaluated whether or not a surface unevenness and pattern isformed on the surface of the prepared film. Evaluation criteria are asfollows.

A: formation of a surface unevenness and pattern is not viewed.

B: the surface unevenness and pattern is slightly recognized at aportion of the surface of the prepared film (less than 10% of the areaof the surface of the prepared film).

C: the surface unevenness and pattern is recognized at a portion of thesurface of the prepared film.

D: the surface unevenness and pattern is uniformly formed on the surfaceof the prepared film (10% or greater of the area of the surface of theprepared film).

Film Strength

The prepared film is punched with a dumbbell No. 3, so as to form asample piece. The sample piece is installed in a tensile tester, andthen an applied load (tensile breaking strength) and elongation at break(tensile elongation at break) when the sample piece is stretched andbroken are measured.

-   -   Test device: tensile tester 1605 type manufactured by Aikoh        engineering Co., Ltd.    -   Length of sample: 30 mm    -   Width of sample: 5 mm    -   Tensile speed: 10 mm/min

Examples 2 to 28

Preparation of Polyimide Precursor Compositions (A-2) to (A-28)

Polyimide precursor compositions (A-2) to (A-28) are prepared in thesame manner as in Example 1 except that the condition of thepolymerization process for the polyimide precursor composition ischanged to conditions shown in Tables 1 to 4.

After the storage stability of the obtained polyimide precursorcompositions is evaluated in the same manner as in Example 1, the filmpreparation properties and the film strength are evaluated. Theevaluation results are shown in Tables 1 to 3 below.

Here, regarding the polyimide precursor compositions (A-2) to (A-28)just after being prepared, the solid content of the polyimide precursor(PI precursor) and the like are also measured in the same manner as inthe case of the polyimide precursor composition (A-1) in Example 1.

Example 29

Solvent Substitution Method

Preparation of Polyimide Precursor Compositions (B-1) and (B-2)

Polymerization Process

A flask equipped with a stirring rod, a thermometer, and a drippingfunnel is filled with 360 g of tetrahydrofuran (THF) and 40 g of water.45.00 g (224.73 mmol) of 4,4′-diaminodiphenyl ether (ODA: molecularweight of 200.24) as the diamine compound and 15.47 g (89.89 mmol) of4-ethynylphthalic anhydride as the acetylene compound are added thereinwhile a dried nitrogen gas is introduced. While stirring is performedand the temperature of the solution is held to 30° C., 55.00 g (186.93mmol) of 3,3′,4,4′-biphenyl tetracarboxylic dianhydride (BPDA: molecularweight of 294.22) as the tetracarboxylic dianhydride are slowly added.Subsequently, while the temperature of the reaction is held to 30° C.,the reaction is performed for 24 hours.

The imidization rate of the produced polyimide precursor is 0.02. Thequantity of the terminal acetylene groups of the polyimide precursor ismeasured as described above. As a result, the polyimide precursor hasacetylene groups at all the terminals.

The obtained polyimide precursor aqueous solution is set as a polyimideprecursor composition (B-1). The composition of the obtained polyimideprecursor composition (B-1) is as follows.

Composition of Polyimide precursor composition (B-1)

-   -   Solid content: 18.5% (solid fraction as polyimide), 20% (solid        content of polyimide precursor)    -   Solvent composition ratio: THF/water=360 g/40 g

Amine-Salt Forming Process

The polyimide precursor solution obtained in the polymerization processis stirred, and 33.33 g (373.87 mmol) of dimethyl aminoethanol (DMAEt:molecular weight of 89.14) as the organic amine compound and 400 g ofwater are added thereto, thereby obtaining a polyimide precursor aqueoussolution in which an amine salt of the polyimide precursor is formed andis dissolved in water.

Solvent Substitution Process

While the obtained polyimide precursor aqueous solution is stirred,pressure is reduced at 10 mmHg/30° C. to distill away a portion of theTHF. Thus, a polyimide precursor composition (B-2) having the followingcomposition is obtained.

Composition of Polyimide Precursor Composition (B-2)

-   -   Viscosity: 20 Pas    -   Solid content: 18.0% (solid fraction as polyimide), 18.8% (solid        content of polyimide precursor)    -   Solvent composition ratio: THF/water=6/94

After the storage stability of the obtained polyimide precursorcompositions is evaluated in the same manner as in Example 1, the filmpreparation properties and the film strength are evaluated. Theevaluation results are shown in Table 4 below.

Examples 29 to 37

Preparation of Polyimide Precursor Compositions (B-3) and (B-11)

Polyimide precursor compositions (B-3) to (B-11) are prepared in thesame manner as in Example 26 except that the condition of thepolymerization process for the polyimide precursor composition ischanged to conditions shown in Tables 1 to 4.

After the storage stability of the obtained polyimide precursorcompositions is evaluated in the same manner as in Example 1, the filmpreparation properties and the film strength are evaluated. Theevaluation results are shown in Table 4 below.

Here, regarding the polyimide precursor compositions (B-3) to (B-11)just after being prepared, the solid content of polyimide and the likeare also measured in the same manner as in the case of the polyimideprecursor composition (A-1) in Example 1.

Comparative Example 1

Preparation of Polyimide Precursor Composition (X-1)

A polyimide precursor composition (X-1) is prepared in the same manneras in the case of the polyimide precursor composition (A-2) in Example 2except that 3-ethynylaniline is not added (the amount of each componentis changed in accordance with Table 5). When the liquid state of (X-1)after being stored at room temperature (25° C.) for 20 days isrecognized, viscosity is increased and stringiness occurs.

After the storage stability of the prepared polyimide precursorcomposition is evaluated in the same manner as in Example 1, the filmpreparation properties and the film strength are evaluated. Theevaluation results are shown in Table 5 below.

When the liquid state of (X-1) and the liquid state of (A-2) after thestorage stability (that is, after the composition is stored under anenvironment of room temperature (25° C.) and 20 days) are compared, thepolyimide precursor in (A-2) is stably dissolved almost in a uniformstate. However, in (X-1), viscosity is increased and stringinessintensively occurs. The imidization rate of (X-1) is 0.35, and thusimidization remarkably proceeds. In a molded article obtained by using(X-1), the void trace and the surface unevenness and pattern areincreased, and the strength is lowered than that of the molded articleobtained by using (A-2).

Comparative Example 2

Preparation of Polyimide Precursor Composition (X-2)

A polyimide precursor composition (X-2) is prepared in the same manneras in the case of the polyimide precursor composition (A-2) in Example 2except that 3-ethynylaniline is not added (the amount of each componentis changed in accordance with Table 5). The concentration of (X-2) isset to be lower than that of (X-1) in order to improve the storagestability. When the liquid state of (X-2) after being stored at roomtemperature (25° C.) for 20 days is recognized, an increase of theviscosity is prevented as compared with that in (X-1), but stringinessoccurs. In a molded article obtained by using (X-2), the results interms of the void trace and the surface unevenness and pattern arebetter than those of the molded article obtained by using (X-1).However, the strength is still low, as well as that of the moldedarticle obtained by using (X-1).

Comparative Example 3

Preparation of Polyimide Precursor Composition (X-3)

A polyimide precursor composition (X-3) is prepared in the same manneras in the case of the polyimide precursor composition (A-2) in Example 2except that 3-ethynylaniline is not added (the amount of each componentis changed in accordance with Table 5). When the liquid state of (X-3)after being stored at room temperature (25° C.) for 20 days isrecognized, gelling occurs.

Comparative Example 4

Preparation of Polyimide Precursor Composition (X-4)

A polyimide precursor composition (X-4) is prepared in the same manneras in the case of the polyimide precursor composition (B-1) in Example29 except that 3-ethynylaniline is not added (the amount of eachcomponent is changed in accordance with Table 5). Regarding the liquidstate of (X-4) after being stored at room temperature (25° C.) for 20days, viscosity is increased and stringiness occurs.

TABLE 1 Example Example 1 Example 2 Example 3 Example 4 Example 5Polyimide precursor composition A-1 A-2 A-3 A-4 A-5 SynthesisTetracarboxylic Chemical type BPDA BPDA PMDA BTDA BPDA conditiondianhydride g 70.00 70.00 70.00 70.00 70.00 mmol 237.92 237.92 320.92217.24 237.92 Diamine compound Chemical type PDA ODA ODA PDA ODA g 21.4439.70 53.55 19.58 57.40 mmol 198.26 198.26 267.44 181.03 286.65Tetracarboxylic dianhydride/diamine 1.2 1.2 1.2 1.2 0.83 compound (molarratio) Organic amine Chemical type 1 MMO MMO MMO MMO MMO compound g48.13 48.13 64.92 47.61 48.13 mmol 475.83 475.83 641.85 434.47 475.83Chemical type 2 — — — — — g — — — — — mmol — — — — — Treatment ratio mol% 100 100 100 100 100 Aqueous solvent Chemical type 1 Water Water WaterWater Water g 308 286 313 227 336 Chemical type 2 — DMI DMI DMI DMI g —95 104 76 112 Acetylene Chemical type 3-ethynyl 3-ethynyl 3-ethynyl3-ethynyl 4-ethynyl compound aniline aniline aniline aniline phthalicanhydride g 9.29 9.29 12.53 8.48 13.43 mmol 79.31 79.31 106.97 72.41114.66 Quantity of terminal % 100 100 100 100 100 acetylene Solidcontent of PI % 20 20 20 20 20 precursor Liquid state DissolvedDissolved Dissolved Dissolved Dissolved Imidization ratio 0.02 0.02 0.020.02 0.02 Molecular weight of Mw 10000 10000 10000 10000 10000 PIprecursor PI solid content % 18.5 18.5 18.5 18.5 18.5 Viscosity Pa · s21 18 20 30 19 Storage Storage condition Room Room Room Room Roomstability temperature temperature temperature temperature temperatureand 20 days and 20 days and 20 days and 20 days and 20 days Liquid stateDissolved Dissolved Dissolved Dissolved Dissolved Stringiness A A A A AViscosity Pa · s 21 19 22 29 19 Imidization ratio 0.03 0.03 0.04 0.030.04 Film Void trace A A A A A preparation Surface unevenness andpattern A A A A A properties Film Tensile breaking MPa 320 210 190 310210 strength strength Tensile elongation % 50 90 80 50 90 at breakExample Example 6 Example 7 Example 8 Example 9 Example 10 Polyimideprecursor composition A-6 A-7 A-8 A-9 A-10 Synthesis TetracarboxylicChemical type BPDA BPDA BPDA PMDA BPDA condition dianhydride g 70.0070.00 70.00 70.00 70.00 mmol 237.92 237.92 237.92 320.92 237.92 Diaminecompound Chemical type ODA ODA ODA ODA ODA g 39.70 39.70 45.37 63.0039.70 mmol 198.26 198.26 226.59 314.63 198.26 Tetracarboxylicdianhydride/diamine 1.2 1.2 1.05 1.02 1.2 compound (molar ratio) Organicamine Chemical type 1 DMAEt MMO MMO 2,4,6- morpholine compound collidineg 42.42 48.13 48.13 77.78 41.45 mmol 475.83 475.83 475.83 641.85 475.83Chemical type 2 — — — — — g — — — — — mmol — — — — — Treatment ratio mol% 100 100 100 100 100 Aqueous solvent Chemical type 1 Water Water WaterWater Water g 290 286 302 330 209 Chemical type 2 DMI DMI DMI DMI DMI g97 95 101 110 70 Acetylene compound Chemical type 3-ethynyl 3-ethynyl3-ethynyl 3-ethynyl 3-ethynyl aniline aniline aniline aniline aniline g9.29 9.29 10.62 14.74 9.29 mmol 79.31 79.31 90.64 125.85 79.31 Quantityof terminal % 100 100 100 100 100 acetylene Solid content of PI % 20 2020 20 25 precursor Liquid state Dissolved Dissolved Dissolved DissolvedDissolved Imidization ratio 0.02 0.05 0.05 0.05 0.02 Molecular weight ofMw 10000 5000 50000 100000 2000 PI precursor PI solid content % 18.518.5 18.5 18.5 23.2 Viscosity Pa · s 18 10 90 110 15 Storage Storagecondition Room Room Room Room Room stability temperature temperaturetemperature temperature temperature and 20 days and 20 days and 20 daysand 20 days and 20 days Liquid state Dissolved Dissolved DissolvedDissolved Dissolved Stringiness A A A A A Viscosity Pa · s 18 11 95 11218 Imidization ratio 0.04 0.03 0.05 0.02 0.06 Film Void trace A A A A Apreparation Surface unevenness and pattern A A A A A properties FilmTensile breaking MPa 190 180 200 190 180 strength strength Tensileelongation % 80 75 80 70 75 at break

TABLE 2 Example Example 11 Example 12 Example 13 Example 14 Example 15Polyimide precursor composition A-11 A-12 A-13 A-14 A-15 SynthesisTetracarboxylic Chemical type BPDA BPDA BPDA BPDA BPDA conditiondianhydride g 70.00 70.00 70.00 70.00 70.00 mmol 237.92 237.92 237.92237.92 237.92 Diamine compound Chemical type ODA ODA ODA ODA ODA g 39.7039.70 39.70 39.70 39.70 mmol 198.26 198.26 198.26 198.26 198.26Tetracarboxylic dianhydride/diamine 1.2 1.2 1.2 1.2 1.2 compound (molarratio) Organic amine Chemical type 1 N-ethyl 2-ethyl- 1,2- TEA N-methylcompound morpholine 4-methyl dimethyl piperidine imidazole imidazole g52.42 54.80 45.74 48.15 47.19 mmol 475.83 475.83 475.83 475.83 475.83Chemical type 2 — — — — — g — — — — — mmol — — — — — Treatment ratio mol% 100 100 100 100 100 Aqueous solvent Chemical type 1 Water Water WaterWater Water g 283 281 288 286 287 Chemical type 2 DMI DMI DMI DMI DMI g94 94 96 95 96 Acetylene compound Chemical type 3-ethynyl 3-ethynyl3-ethynyl 3-ethynyl 3-ethynyl aniline aniline aniline aniline aniline g9.29 9.29 9.29 9.29 9.29 mmol 79.31 79.31 79.31 79.31 79.31 Quantity ofterminal % 100 100 100 100 100 acetylene Solid content of PI % 20 20 2020 20 precursor Liquid state Dissolved Dissolved Dissolved DissolvedDissolved Imidization ratio 0.02 0.02 0.02 0.02 0.02 Molecular weight ofMw 10000 10000 10000 10000 10000 PI precursor PI solid content % 18.518.5 18.5 18.5 18.5 Viscosity Pa · s 22 26 28 17 16 Storage Storagecondition Room Room Room Room Room stability temperature temperaturetemperature temperature temperature and 20 days and 20 days and 20 daysand 20 days and 20 days Liquid state Dissolved Dissolved DissolvedDissolved Dissolved Stringiness A A A A A Viscosity Pa · s 22 27 28 1717 Imidization ratio 0.02 0.02 0.02 0.02 0.02 Film Void trace A A A A Apreparation Surface unevenness and pattern A A A A A properties FilmTensile breaking MPa 210 190 190 210 190 strength strength Tensileelongation % 90 80 80 90 80 at break Example Example 16 Example 17Example 18 Example 19 Example 20 Polyimide precursor composition A-16A-17 A-18 A-19 A-20 Synthesis Tetracarboxylic Chemical type CBDA BPDABPDA BPDA BPDA condition dianhydride g 70.00 70.00 70.00 70.00 70.00mmol 356.94 237.92 237.92 237.92 237.92 Diamine compound Chemical type1,6- ODA PDA ODA ODA cyclohexene diamine g 33.97 39.70 21.44 39.70 39.70mmol 297.45 198.26 198.26 198.26 198.26 Tetracarboxylicdianhydride/diamine 1.2 1.2 1.2 1.2 1.2 compound (molar ratio) Organicamine Chemical type 1 MMO MMO MMO MMO MMO compound g 72.21 24.07 48.1348.13 48.13 mmol 713.89 237.92 475.83 475.83 475.83 Chemical type 2 —TEA TEA — — g — 24.07 24.07 — — mmol — 400.48 400.48 — — Treatment ratiomol % 100 100 150 100 100 Aqueous solvent Chemical type 1 Water WaterWater Water Water g 247 304 163 249 423 Chemical type 2 DMI 1-propanol1-methoxy- 1-methoxy- 2-methoxy 2-propanol 2-propanol ethanol g 82 10154 83 141 Acetylene compound Chemical type 3-ethynyl 3-ethynyl 3-ethynyl3-ethynyl 3-ethynyl aniline aniline aniline aniline aniline g 13.94 9.299.29 9.29 9.29 mmol 118.98 79.31 79.31 79.31 79.31 Quantity of terminal% 100 100 100 100 100 acetylene Solid content of PI % 20 20 25 22 15precursor Liquid state Dissolved Dissolved Dissolved Dissolved DissolvedImidization ratio 0.02 0.02 0.02 0.02 0.02 Molecular weight of Mw 1000010000 10000 10000 10000 PI precursor PI solid content % 18.5 18.5 23.220.4 13.9 Viscosity Pa · s 22 19 83 44 10 Storage Storage condition RoomRoom Room Room Room stability temperature temperature temperaturetemperature temperature and 20 days and 20 days and 20 days and 20 daysand 20 days Liquid state Dissolved Dissolved Dissolved DissolvedDissolved Stringiness A A A A A Viscosity Pa · s 22 19 87 46 11Imidization ratio 0.04 0.05 0.05 0.05 0.03 Film Void trace A A A A Apreparation Surface unevenness and pattern A A A A A properties FilmTensile breaking MPa 340 210 320 190 200 strength strength Tensileelongation % 50 90 45 75 80 at break

TABLE 3 Example Example 21 Example 22 Example 23 Example 24 Polyimideprecursor composition A-21 A-22 A-23 A-24 Synthesis TetracarboxylicChemical type BPDA BPDA BPDA BPDA condition dianhydride g 70.00 70.0070.00 70.00 mmol 237.92 237.92 237.92 237.92 Diamine compound Chemicaltype ODA ODA ODA ODA g 39.70 39.70 39.70 39.70 mmol 198.26 198.26 198.26198.26 Tetracarboxylic dianhydride/diamine 1.2 1.2 1.2 1.2 compound(molar ratio) Organic amine Chemical type 1 MMO MMO MMO MMO compound g48.13 48.13 48.15 45.74 mmol 475.83 475.83 475.83 475.83 Chemical type 2— — — — g — — — — mmol — — — — Treatment ratio mol % 100 100 100 100Aqueous solvent Chemical type 1 Water Water Water Water g 293 291 288289 Chemical type 2 DMI DMI DMI DMI g 98 97 96 96 Acetylene compoundChemical type 3-ethynyl 3-ethynyl 3-ethynyl 3-ethynyl aniline anilineaniline aniline g 0.46 2.79 6.50 8.36 mmol 3.97 23.79 55.51 71.38Quantity of terminal % 5 30 70 90 acetylene Solid content of PI % 20 2020 20 precursor Liquid state Dissolved Dissolved Dissolved DissolvedImidization ratio 0.02 0.02 0.02 0.02 Molecular weight of Mw 10000 1000010000 10000 PI precursor PI solid content % 18.5 18.5 18.5 18.5Viscosity Pa · s 21 22 20 20 Storage Storage condition Room Room RoomRoom stability temperature temperature temperature temperature and 20days and 20 days and 20 days and 20 days Liquid state DissolvedDissolved Dissolved Dissolved Stringiness B B B A Viscosity Pa · s 45 3022 20 Imidization ratio 0.02 0.02 0.02 0.02 Film Void trace A A A Apreparation Surface unevenness and pattern B B A A properties FilmTensile breaking MPa 170 195 200 230 strength strength Tensileelongation % 75 85 85 90 at break Example Example 25 Example 26 Example27 Example 28 Polyimide precursor composition A-25 A-26 A-27 A-28Synthesis Tetracarboxylic Chemical type BPDA BPDA BPDA BPDA conditiondianhydride g 70.00 70.00 70.00 70.00 mmol 237.92 237.92 237.92 237.92Diamine compound Chemical type ODA ODA ODA ODA g 39.70 39.70 39 70 39.70mmol 198.26 198.26 198.26 198.26 Tetracarboxylic dianhydride/diamine 1.21.2 1.2 1.2 compound (molar ratio) Organic amine Chemical type 1 MMO MMOMMO MMO compound g 45.74 45.74 45.74 45.74 mmol 475.83 475.83 475.83475.83 Chemical type 2 — — — — g — — — — mmol — — — — Treatment ratiomol % 100 30 50 75 Aqueous solvent Chemical type 1 Water Water WaterWater g 288 288 288 288 Chemical type 2 DMI DMI DMI DMI g 96 96 96 96Acetylene compound Chemical type 4-ethynyl 3-ethynyl 3-ethynyl 3-ethynylaniline aniline aniline aniline g 9.29 9.29 9.29 9.29 mmol 79.31 79.3179.31 79.31 Quantity of terminal % 100 100 100 100 acetylene Solidcontent of PI % 20 20 20 20 precursor Liquid state Dissolved DissolvedDissolved Dissolved Imidization ratio 0.02 0.02 0.02 0.02 Molecularweight of Mw 10000 10000 10000 10000 PI precursor PI solid content %18.5 18.5 18.5 18.5 Viscosity Pa · s 20 55 40 34 Storage Storagecondition Room Room Room Room stability temperature temperaturetemperature temperature and 20 days and 20 days and 20 days and 20 daysLiquid state Dissolved Dissolved Dissolved Dissolved Stringiness A A A AViscosity Pa · s 20 65 44 35 Imidization ratio 0.02 0.02 0.02 0.02 FilmVoid trace A A A A preparation Surface unevenness and pattern A A A Aproperties Film Tensile breaking MPa 190 210 220 230 strength strengthTensile elongation % 70 75 75 85 at break

TABLE 4 Example•Comparative Example Example 29 Example 30 Example 31Example 32 Polyimide precursor composition B-1 B-2 B-3 B-4 B-5Polymerization Tetracarboxylic Chemical type BPDA BPDA BPDA BPDA BPDAprocess dianhydride g 55 55 55 55 55 mmol 186.93 186.93 186.93 186.93186.93 Diamine compound Chemical type ODA ODA ODA ODA ODA g 45 45 45 4545 mmol 224.73 224.73 224.73 224.73 224.73 Tetracarboxylicdianhydride/diamine 0.83 0.83 0.83 0.83 0.83 compound (molar ratio)Solvent 1 Chemical type THF THF THF THF THF g 360 360 360 360 360Solvent 2 Chemical type Water Water Water Water Water g 40 40 40 40 40Solvent 1/solvent 2 9/1 9/1 9/1 9/1 9/1 Acetylene compound Chemical type4-ethynyl 4-ethynyl 4-ethynyl 4-ethynyl 4-ethynyl phthalic phthalicphthalic phthalic phthalic anhydride anhydride anhydride anhydrideanhydride g 15.47 15.47 15.47 15.47 15.47 mmol 89.89 89.89 89.89 89.8989.89 Quantity of terminal acetylene 100 100 100 100 100 Liquid stateDissolved Dissolved Dissolved Dissolved Dissolved Imidization ratio 0.020.02 0.02 0.02 0.02 Molecular weight of Mw 10000 10000 10000 10000 10000PI precursor PI solid content % 20 20 20 20 20 Viscosity Pa · s 20 21 2520 22 Amine-salt Organic amine Chemical type — DMAEt DMAEt DMAEt DMAEtforming compound g — 33.33 16.66 166.63 25.00 process mmol — 373.87186.93 1869.35 280.40 Added solvent Chemical type — Water Water WaterWater g — 400 400 400 300 Treatment ratio mol % — 100 50 500 75 Liquidstate — — Dissolved Dissolved Dissolved Solvent Liquid state — —Dissolved Dissolved Dissolved substitution Molecular weight of % — 18.818.8 18.8 14.6 process PI precursor PI solid content % — 18 18 18 14Viscosity Pa · s — 20 26 18 30 Moisture content in % — 94 98 86 50solvent Storage Storage condition Room Room Room Room Room stabilitytemperature temperature temperature temperature temperature and 20 daysand 20 days and 20 days and 20 days and 20 days Liquid state DissolvedDissolved Dissolved Dissolved Dissolved Stringiness A A A A A ViscosityPa · s 22 22 26 21 22 Imidization ratio 0.03 0.03 0.03 0.03 0.03 FilmVoid trace — A A A A preparation Surface unevenness and pattern — A A AA properties Film strength Tensile breaking MPa — 190 200 210 230strength Tensile elongation % — 80 75 80 90 at break Example•ComparativeExample Example 33 Example 34 Example 35 Example 36 Example 37 Polyimideprecursor composition B-6 B-7 B-8 B-9 B-10 PolymerizationTetracarboxylic Chemical type BPDA BPDA BPDA BPDA BPDA processdianhydride g 55 55 55 55 55 mmol 186.93 186.93 186.93 186.93 186.93Diamine compound Chemical type ODA ODA ODA ODA ODA g 45 45 45 45 45 mmol224.73 224.73 224.73 224.73 224.73 Tetracarboxylic dianhydride/diamine0.83 0.83 0.83 0.83 0.83 compound (molar ratio) Solvent 1 Chemical typeTHF THF THF 1,4-dioxane Acetone g 360 360 360 320 320 Solvent 2 Chemicaltype Water Water Water Water Water g 40 40 40 80 80 Solvent 1/solvent 29/1 9/1 9/1 8/2 8/2 Acetylene compound Chemical type 4-ethynyl 4-ethynyl4-ethynyl 4-ethynyl 4-ethynyl phthalic phthalic phthalic phthalicphthalic anhydride anhydride anhydride anhydride anhydride g 15.47 15.4715.47 15.47 15.47 mmol 89.89 89.89 89.89 89.89 89.89 Quantity ofterminal acetylene 100 100 100 100 100 Liquid state Dissolved DissolvedDissolved Dissolved Dissolved Imidization ratio 0.02 0.02 0.02 0.05 0.08Molecular weight of Mw 10000 10000 10000 10000 10000 PI precursor PIsolid content % 20 20 20 20 20 Viscosity Pa · s 22 23 25 20 20Amine-salt Organic amine Chemical type γ-Pyc MAEt Eta DMAEt DMAEtforming compound g 34.82 28.08 22.84 33.33 33.33 process mmol 373.87373.87 373.87 373.87 373.87 Added solvent Chemical type Water WaterWater Water Water g 400 400 400 400 400 Treatment ratio mol % 100 100100 100 100 Liquid state Dissolved Dissolved Dissolved DissolvedDissolved Solvent Liquid state Dissolved Dissolved Dissolved DissolvedDissolved substitution Molecular weight of % 18.8 18.8 18.8 15.7 18.8process PI precursor PI solid content % 18 18 18 15 18 Viscosity Pa · s26 23 24 30 32 Moisture content in % 92 90 88 92 96 solvent StorageStorage condition Room Room Room Room Room stability temperaturetemperature temperature temperature temperature and 20 days and 20 daysand 20 days and 20 days and 20 days Liquid state Dissolved DissolvedDissolved Dissolved Dissolved Stringiness A A A A A Viscosity Pa · s 2224 24 21 22 Imidization ratio 0.03 0.03 0.03 0.03 0.03 Film Void trace AA A A A preparation Surface unevenness and pattern A A A B B propertiesFilm strength Tensile breaking MPa 200 195 200 220 230 strength Tensileelongation % 85 80 75 90 80 at break

TABLE 5 Comparative Comparative Comparative Comparative Example Example1 Example 2 Example 3 Polyimide precursor composition X-1 X-2 X-3Synthesis Tetracarboxylic dianhydride Chemical type BPDA BPDA BPDAcondition g 55 55 55 mmol 186.93 186.93 186.93 Diamine compound Chemicaltype ODA ODA ODA g 45 45 45 mmol 224.73 224.73 224.73 Tetracarboxylicdianhydride/diamine 0.9 0.9 0.99 compound (molar ratio) Organic aminecompound Chemical type 1 MMO MMO MMO g 37.82 37.82 37.82 mmol 373.87373.87 373.87 Chemical type 2 — — — g — — — mmol — — — Treatment ratiomol % 100 100 100 Aqueous solvent Chemical type 1 Water Water Water g272 474 474 Chemical type 2 DMI DMI DMI g 91 158 158 Acetylene compoundChemical type — — — g — — mmol — — — Quantity of terminal acetylene % 00 0 Solid content of PI precursor % 20 13 13 Liquid state DissolvedDissolved Dissolved Imidization ratio 0.02 0.02 0.02 Molecular weight ofPI precursor Mw 10000 10000 100000 PI solid content % 18.5 12.1 12.1Viscosity Pa · s 30 38 130 Terminal amino group Contained ContainedContained Storage Storage condition Room Room Room stability temperaturetemperature temperature and 20 days and 20 days and 20 days Liquid stateDissolved Dissolved Gelling Stringiness D D — Viscosity Pa · s 210 45 —Imidization ratio 0.35 0.08 0.3 Film Void trace C A — preparationSurface unevenness and pattern B B — properties Film strength Tensilebreaking strength MPa 85 90 — Tensile elongation at break % 13 25 —

TABLE 6 Comparative Example•Comparative Example Example 4 Polyimideprecursor composition X-4 Polymerization Tetracarboxylic Chemical typeBPDA process dianhydride g 55 mmol 186.93 Diamine compound Chemical typeODA g 45 mmol 224.73 Tetracarboxylic dianhydride/diamine 0.83 compound(molar ratio) Solvent 1 Chemical type THF g 360 Solvent 2 Chemical typeWater g 40 Solvent 1/solvent 2 9/1 Acetylene compound Chemical type — g— mmol — Quantity of terminal acetylene 0 Liquid state DissolvedImidization ratio 0.02 Molecular weight of PI Mw 5000 precursor PI solidcontent % 20 Viscosity Pa · s 20 Amine-salt Organic amine Chemical type— forming compound g — process mmol — Added solvent Chemical type — g —Treatment ratio mol % — Liquid state — Solvent Liquid state —substitution Molecular weight of PI % — process precursor PI solidcontent % — Viscosity Pa · s — Moisture content in % — solvent StorageStorage condition Room stability temperature and 20 days Liquid stateDissolved Stringiness D Viscosity Pa · s 190 Imidization ratio 0.1 Filmpreparation Void trace — properties Surface unevenness and pattern —Film strength Tensile breaking MPa — strength Tensile elongation at % —break

From the results, it is found that favorable results for evaluation ofthe storage stability of the polyimide precursor composition areobtained in these examples as compared with the comparative examples.

It is found that favorable results for evaluation of the coatingstability and the film preparation properties of the polyimide precursorcomposition are also obtained in these examples as compared with thecomparative examples. It is found that favorable results for evaluationof the mechanical strength are also obtained in these examples.

Abbreviations and the like in Table 1 to Table 6 are as follows. “-” inTable 1 to Table 5 means being not added or being not performed.

Tetracarboxylic dianhydride: “BPDA” (3,3′,4,4′-biphenyl tetracarboxylicdianhydride), “PMDA” (pyromelletic dianhydride), “BTDA” (benzophenonetetracarboxylic dianhydride), and “CBDA”(cyclobutane-1,2:3,4-tetracarboxylic dianhydride)

-   -   Diamine compound: “ODA” (4,4′-diaminodiphenyl ether) and “PDA”        (p-phenylenediamine)    -   Organic amine compound: MMO (methyl morpholine: tertiary amine        compound: boiling point of 115° C. to 116° C.), 2,4,6-collidine        (tertiary amine compound: molecular weight of 121.18, boiling        point of 171° C.), morpholine (secondary amine compound:        molecular weight of 87.1, boiling point of 129° C.), ethyl        morpholine (tertiary amine compound: molecular weight of 115.17,        boiling point of 139° C.), 2-ethyl-4-methylimidazole (tertiary        amine compound: molecular weight of 110.16, boiling point of        292° C. to 295° C.), DMAEt (dimethyl aminoethanol: tertiary        amine compound: boiling point of 133° C. to 134° C.), TEA        (triethanolamine: tertiary amine compound: boiling point of 360°        C.), and N-methyl piperidine (tertiary amine compound: 106° C.        to 107° C.)    -   Solvent: THF (tetrahydrofuran: water-soluble ether solvent:        boiling point of 67° C.), NMP (N-methyl-2-pyrrolidone), and DMI        (1,3-dimethyl-2-imidazolidinone, boiling point: 224° C. to 226°        C.)

In the examples, “a treatment ratio” means the quantity (mol %) of theorganic amine compound with respect to the theoretical amount of thecarboxy group included in the polyimide precursor. Here, the theoreticalamount of the carboxy group represents a value obtained by doubling themolar amount of the tetracarboxylic dianhydride used in the polyimideprecursor.

The foregoing description of the exemplary embodiments of the presentinvention has been provided for the purposes of illustration anddescription. It is not intended to be exhaustive or to limit theinvention to the precise forms disclosed. Obviously, many modificationsand variations will be apparent to practitioners skilled in the art. Theembodiments were chosen and described in order to best explain theprinciples of the invention and its practical applications, therebyenabling others skilled in the art to understand the invention forvarious embodiments and with the various modifications as are suited tothe particular use contemplated. It is intended that the scope of theinvention be defined by the following claims and their equivalents.

What is claimed is:
 1. A polyimide precursor composition comprising asolvent and a polyimide precursor including a group having a triple bondat a terminal thereof, which is dissolved in the solvent, wherein thesolvent comprises water and a compound selected from the groupconsisting of morpholines and amino alcohols, and wherein a content ofthe compound selected from the group consisting of morpholines and aminoalcohols is from 80 mol % to 120 mol % with respect to a carboxy group(—COOH) of the polyimide precursor in the polyimide precursorcomposition.
 2. The polyimide precursor composition according to claim1, wherein a content of the polyimide precursor is from 10% by weight to50% by weight with respect to the polyimide precursor composition. 3.The polyimide precursor composition according to claim 1, wherein thegroup having a triple bond is at least one group selected from the groupconsisting of an alkynyl group having 2 to 10 carbon atoms.
 4. Thepolyimide precursor composition according to claim 3, wherein the grouphaving a triple bond is an acetylene group.
 5. The polyimide precursorcomposition according to claim 1, wherein a ratio of the number of thegroup having a triple bond with respect to the number of all theterminals of the polyimide precursor is from 90 mol % to 100 mol %. 6.The polyimide precursor composition according to claim 1, wherein aweight average molecular weight of the polyimide precursor is from50,000 to 200,000.
 7. The polyimide precursor composition according toclaim 1, wherein the polyimide precursor is a condensation polymer of anaromatic tetracarboxylic dianhydride and an aromatic diamine compound, aterminal of the condensation polymer being sealed by a compound whichincludes not only a group including a triple bond, but also a carboxygroup or an amino group.
 8. The polyimide precursor compositionaccording to claim 2, wherein a ratio of the number of the group havinga triple bond with respect to the number of all the terminals in thepolyimide precursor is from 90 mol % to 100 mol %.
 9. The polyimideprecursor composition according to claim 1, wherein the solventincluding water includes water in an amount of 50% by weight or morewith respect to the entirety of the solvent.
 10. A method of preparing apolyimide molded article, which comprises heating the polyimideprecursor composition according to claim 1.